This NSA classification guide, dated 21 November 2011, covers signals intelligence material that as to be kept secret for more than the standard 60 years: see the Der Spiegel article The NSA in Germany: Snowden’s Documents Available for Download, 18 June 2014.

This internal NSA post from September 2006 describes the evolution of the European Security Operations Center and the focus of the US-German collaboration in signals intelligence: see the Der Spiegel article Terrorverdächtige: NSA nutzte Erkenntnisse aus Deutschland-Filiale für Tötungen, 15 June 2014.

﻿(U//FOUOKTh^European. Security Center to Become the 'ESOC'
FROM:
A&P‘s Director, Enterprise Management (S2)
Run Date: 09/11/2006
(S//SI) NSA to help build up capabilities of the intell...